diff --git a/lib/secretariat/constants.rb b/lib/secretariat/constants.rb
index 30f2ae7..291c1fa 100644
--- a/lib/secretariat/constants.rb
+++ b/lib/secretariat/constants.rb
@@ -53,6 +53,10 @@ module Secretariat
    :DEBITADVICE => "31",
    :CREDITCARD => "48",
    :DEBIT => "49",
+   :CREDITTRANSFER => "54",
+   :DIRECTDEBIT => "55",
+   :SEPACREDITTRANSFER => "58",
+   :SEPADIRECTDEBIT => "59",
    :COMPENSATION => "97"
   }
 
diff --git a/lib/secretariat/invoice.rb b/lib/secretariat/invoice.rb
index 4e88664..05af4e6 100644
--- a/lib/secretariat/invoice.rb
+++ b/lib/secretariat/invoice.rb
@@ -48,6 +48,9 @@ module Secretariat
     :tax_calculation_method,
     :notes,
     :attachments,
+    :direct_debit_mandate_reference_id, # BT-89
+    :direct_debit_creditor_id, # BT-90
+    :direct_debit_iban, # BT-91
     keyword_init: true
   ) do
 
@@ -260,6 +263,9 @@ def to_xml(version: 1, validate: true)
             end
             trade_settlement = by_version(version, 'ApplicableSupplyChainTradeSettlement', 'ApplicableHeaderTradeSettlement')
             xml['ram'].send(trade_settlement) do
+              if direct_debit_creditor_id
+                xml['ram'].CreditorReferenceID direct_debit_creditor_id # BT-90
+              end
               if payment_reference.present?
                 xml['ram'].PaymentReference payment_reference
               end
@@ -278,6 +284,11 @@ def to_xml(version: 1, validate: true)
                     xml['ram'].BICID payment_bic
                   end
                 end
+                if direct_debit_iban
+                  xml['ram'].PayerPartyDebtorFinancialAccount do
+                    xml['ram'].IBANID direct_debit_iban
+                  end
+                end
               end
               taxes.each do |tax|
                 xml['ram'].ApplicableTradeTax do
@@ -311,6 +322,9 @@ def to_xml(version: 1, validate: true)
                     Helpers.date_element(xml, payment_due_date)
                   end
                 end
+                if direct_debit_mandate_reference_id
+                  xml['ram'].DirectDebitMandateID direct_debit_mandate_reference_id
+                end
               end
 
               monetary_summation = by_version(version, 'SpecifiedTradeSettlementMonetarySummation', 'SpecifiedTradeSettlementHeaderMonetarySummation')
diff --git a/test/invoice_test.rb b/test/invoice_test.rb
index cf7fbb7..9115b4d 100644
--- a/test/invoice_test.rb
+++ b/test/invoice_test.rb
@@ -57,6 +57,64 @@ def make_eu_invoice(tax_category: :REVERSECHARGE)
       )
     end
 
+    def make_eu_invoice_with_sepa_direct_debit(tax_category: :REVERSECHARGE)
+      seller = TradeParty.new(
+        name: 'Depfu inc',
+        street1: 'Quickbornstr. 46',
+        city: 'Hamburg',
+        postal_code: '20253',
+        country_id: 'DE',
+        vat_id: 'DE304755032'
+      )
+      buyer = TradeParty.new(
+        name: 'Depfu inc',
+        street1: 'Quickbornstr. 46',
+        city: 'Hamburg',
+        postal_code: '20253',
+        country_id: 'SE',
+        vat_id: 'SE304755032'
+      )
+      line_item = LineItem.new(
+        name: 'Depfu Premium Plan',
+        quantity: 1,
+        gross_amount: BigDecimal('29'),
+        net_amount: BigDecimal('29'),
+        unit: :YEAR,
+        charge_amount: BigDecimal('29'),
+        tax_category: tax_category,
+        tax_percent: 0,
+        tax_amount: 0,
+        origin_country_code: 'DE',
+        currency_code: 'EUR',
+        service_period_start: Date.today,
+        service_period_end: Date.today + 364,
+      )
+      Invoice.new(
+        id: '12345',
+        issue_date: Date.today,
+        # service_period on line_item. removed here to simplify testing of BillingSpecifiedPeriod presence
+        # service_period_start: Date.today,
+        # service_period_end: Date.today + 30,
+        seller: seller,
+        buyer: buyer,
+        line_items: [line_item],
+        currency_code: 'USD',
+        payment_type: :CREDITCARD,
+        payment_text: 'Kreditkarte',
+        tax_category: tax_category,
+        tax_amount: 0,
+        basis_amount: BigDecimal('29'),
+        grand_total_amount: BigDecimal('29'),
+        due_amount: 0,
+        paid_amount: 29,
+        payment_due_date: Date.today + 14,
+        notes: "This is a test invoice",
+        direct_debit_mandate_reference_id: "MANDATE REFERENCE", # BT-89
+        direct_debit_creditor_id: "DE98ZZZ09999999999", # BT-90
+        direct_debit_iban: "DE02120300000000202051", # BT-91
+      )
+    end
+
     def make_foreign_invoice(tax_category: :TAXEXEMPT)
       seller = TradeParty.new(
         name: 'Depfu inc',
@@ -381,6 +439,30 @@ def test_simple_eu_invoice_v2
       puts e.errors
     end
 
+    def test_simple_eu_invoice_v2_with_sepa_direct_debit
+      begin
+        xml = make_eu_invoice_with_sepa_direct_debit.to_xml(version: 2)
+      rescue ValidationError => e
+        pp e.errors
+      end
+
+      assert_match(%r{<ram:CreditorReferenceID>DE98ZZZ09999999999</ram:CreditorReferenceID>}, xml)
+      assert_match(%r{<ram:PayerPartyDebtorFinancialAccount>\s*<ram:IBANID>DE02120300000000202051\s*</ram:IBANID>}, xml)
+      assert_match(%r{<ram:DirectDebitMandateID>MANDATE REFERENCE</ram:DirectDebitMandateID>}, xml)
+
+      v = Validator.new(xml, version: 2)
+      errors = v.validate_against_schema
+      if !errors.empty?
+        puts xml
+        errors.each do |error|
+          puts error
+        end
+      end
+      assert_equal [], errors
+    rescue ValidationError => e
+      puts e.errors
+    end
+
     def test_simple_foreign_invoice_v2_taxexpempt
       begin
         xml = make_foreign_invoice(tax_category: :TAXEXEMPT).to_xml(version: 2)